Fluid-delivery device for shafts

ABSTRACT

The invention relates to a fluid delivery device for shafts, with a shaft-ring section assigned to the shaft, which rotates with the shaft during rotation of the shaft and a ring body arranged around the shaft ring section, fixed during rotation of the shaft, which has an inlet for the fluid, rolling bodies being arranged between the shaft ring section and the ring body, on which the shaft ring section and the ring body are supported and a passage being assigned to the shaft ring section, which is connected to inlet.

The invention relates to a fluid-delivery device for shafts. In particular, the invention concerns a central lubrication device for lubrication of drive-shaft bearings and drive-shaft compensation with lubricants, preferably grease.

In practice, lubrication of drive shafts is indispensable. Lubrication must be performed at regular intervals. If this is not done reliably, premature wear of joints can occur. This is a gradual process. It begins by joints showing increasingly greater tolerances. Especially in areas in which machining or production occurs with high precision, this is extremely undesirable and can lead to rejection of the manufactured products. Moreover, the shafts themselves can be damaged. Under some circumstances this leads to rather significant costs for restoration.

Regular lubrication is therefore essential to avoid the problems just mentioned. In rolling operations, for example, the rollers are stopped for this purpose, lubrication is carried out while they are stopped, and the rollers restarted again. This procedure is demanding, but so far, it has been common practice. If the high costs of shutdowns in a rolling mill are considered (1 hour of shutdown can amount to about 100,000.00 ∈) the demand for alternative solutions is obvious.

A central lubrication device for drive shafts is known from DE 8206781.3 U1, which has a drive-shaft ring rotating with the drive shaft and a fixed stator ring that is sealed with respect to the drive shaft. The stator ring has a lubricant inlet, through which lubricant is introduced and injected into the drive shaft ring via a groove. Lines that rotate with the shaft and are brought directly to the shaft joints emerge from the drive-shaft ring. The lubricant can be delivered there with precision in terms of location.

The basic principle of a central lubrication device has significant advantages over ordinary lubrication. In particular, lubrication can occur during operation. Consequently, the drive shafts no longer need to be stopped for lubrication. The already known central lubrication device, however, also has serious shortcomings. Leakage losses are possible in practice, especially during additional radial loading of the central lubrication device. A number of seals are provided, which are supposed to seal the drive shaft ring with respect to the stator ring, but the present invention is based on the finding that translatory relative movements can occur between the drive shaft ring and the stator ring, which then lead to a reduction or even elimination of the sealing effect of the seals.

Another serious shortcoming of the known central lubrication device is that the stator ring is secured axially only by radial shoulders of the drive shaft ring and rotating body, on the one hand, and by a securing connector, on the other hand. This type of arrangement is suitable for horizontal incorporation, under some circumstances, but in certain operating situations, strain can occur between the rotating drive-shaft ring and the fixed stator element. This manifests itself initially by friction losses, which can actually culminate in true seizing. Such friction losses and possibly distortion can occur, in particular, if the known central lubrication device is used on drive shafts that have mounting positions other than horizontal, for example, an angle of 45°.

Starting from the known central lubrication device, the invention is based on the task of devising a fluid-delivery arrangement that offers more reliable sealing and also withstands the additional axial and/or radial forces better, while eliminating the above-mentioned drawbacks.

This task is solved according to the invention by a fluid-delivery device for shafts with a shaft-ring section assigned to the shaft, which rotates with the shaft during rotation of the shaft and with a ring body arranged around the shaft-ring section that is fixed during rotation of the shaft and has an inlet for the valve, rolling bodies being arranged between the shaft-ring section and the ring body on which the shaft ring section and the ring body are supported and in which a passage is assigned to the shaft-ring section, which is connected to the inlet. The shaft-ring section is preferably designed as a shaft ring that is firmly connected to the shaft.

The invention has significant advantages over the known central lubrication device. The rolling bodies always keep the shaft-ring section and the fixed ring at a defined spacing with respect to each other. This means that the seals are always in a defined position, regardless of whether radial forces are acting on the fluid-delivery device or not.

The rolling bodies also permit relative movement of the shaft-ring section with respect to the ring body, which is essentially independent of the circumferential velocity of the shaft. In the known central lubrication device, on the other hand, situations can occur in which unfavorable flow conditions in the gap between the drive-shaft ring and the fixed-ring body (stator ring) lead to friction losses or lubricant escape.

The invention also has the additional significant advantage that shafts with the fluid-delivery device according to the invention can also take up axial forces within certain limits without intolerable friction losses having to be feared. This also permits mounting of shafts at an angle of up to 90° (vertical position).

The rolling bodies are preferably designed as spheres. Roller, barrel-roller or needle-roller bearings are likewise conceivable.

An arrangement in which the rolling bodies are arranged in the flow path of a fluid is particularly advantageous. During use of a lubricant, the friction sites between the ring body, the rolling bodies, and the shaft ring (section) are already sufficiently lubricated by passage of the lubricant. Separate lubrication can be omitted. The rolling bodies are preferably enclosed in a fluid-tight manner by the shaft ring (section) and by the ring body. It is then appropriate for the lubricant passing through the ring body and entering the shaft ring (section) to simultaneously lubricate the seals provided. This design significantly increases the lifetime of the fluid-delivery device according to the invention.

The invention can be mounted on the shaft already at the plant or, as an alternative, retrofitted. In each case, it is particularly advantageous, if the shaft ring is designed in several parts. Opening and closing the fluid delivery device for purposes of inspection or replacement of worn parts is thereby made possible. A two-part shaft ring has worked as a specific design, the two parts of which can be inserted one into the other on the shaft, so that the upper shoulder of one part of the shaft ring overlaps a lower shoulder of the other part of the shaft ring. Both shaft-ring sections can be secured to each other by one or more threaded connections, in which one of the parts can be welded onto the shaft for fastening on the shaft. As an alternative, it can be envisioned that, in addition to the two shaft ring parts, a third ring section is provided, which is firmly welded to the shaft and screwed to the (partial) shaft ring.

A significant further development of the invention is characterized in that the shaft ring (section) forms bearing surfaces for the rolling bodies. An inner and outer ring therefore need not be used, as is common in ordinary bearings, but instead the shaft ring (section) itself and also preferably the ring body form the running or bearing surfaces between which the rolling bodies run. With an appropriate number of rolling bodies, a bearing cage is unnecessary, since the rolling bodies are mutually held in position. The lubricant can pass through the rolling-body ring without problem and simultaneously ensures excellent lubrication of the rolling body itself. A stable and especially space-saving arrangement is also produced. This is especially true when the shaft ring has an outlet for the fluid arranged laterally (axially).

The bearing surfaces are preferably sloped toward the longitudinal axis of the shaft. This permits a take-up of axial forces, which occur, for example, when the entire drive shaft is operated at an angle to the horizontal. Despite such axial (and possibly also radial) components, easy relative movement is always guaranteed between the shaft ring and the ring body.

As already stated, the shaft ring can be designed in several parts. This not only permits simple assembly, but also creates a possibility for inspection or replacement of individual, possibly worn components. It is appropriate, as an alternative or in addition, for the ring body also to be designed in several parts, preferably being capable of disassembly, so that when the fluid-delivery device is fully installed, at least one seal is accessible by removing part of the ring body. The shaft ring arranged on the inside can remain installed during replacement of the seal(s). Only the corresponding ring-body parts need be removed in order to reach the seals. These ring-body parts can, in turn, consist of corresponding ring sections that are mounted laterally on the main ring of the main ring body.

The shaft ring preferably has at least one essentially axial passage for a fluid line. In this way, a fluid line can be guided close to the axis into an area “behind” the fluid delivery device, in order to supply the friction sites arranged there. The passage can be designed as a simple coaxial hole through the shaft ring, optionally designed in several parts.

In a significant further development of the invention, it is proposed that a progressive distributor be provided, which is connected to the shaft ring in terms of flow and rotates with the shaft. The progressive distributor is generally supplied only by a single line that connects the progressive distributor to the fluid-delivery device. The progressive distributor itself distributes the lubricant to the individual lubricating sites through different outlets.

The distributor operates automatically. Several pistons are arranged on the distributor housing, which move back and forth because of the lubricant pressure and therefore guide the lubricant to the different outlets in succession. At lower shaft speeds, no counterweight to the progressive distributor is required on the shaft. Only at higher speeds (for example, beyond 500 rpm) can counterweights be necessary.

The invention will be further explained below by means of a preferred embodiment example in conjunction with the attached drawing. In the drawing:

FIG. 1 shows schematically a drive shaft with a fluid-delivery device according to the invention mounted on it;

FIG. 2 shows an enlarged sectional view of the fluid-delivery device according to FIG. 1 according to the invention.

FIG. 1 shows a drive shaft 1, which is suspended as a Cardan shaft. The invention is preferably applied to this type of drive shaft. A total of nine lubricating sites are present, namely, four lubricating sites 2 to 5 shown on the left side in FIG. 1 and also four lubricating sites 6 to 9 shown on the right side of FIG. 1. The ninth lubricating site is situated roughly in the center of the drive shaft, where a length-compensation device 10 is arranged.

A fluid delivery device 11 according to the invention is arranged on the shaft, in the present case to supply lubricating sites 2 to 10 with lubricant. For this purpose, the fluid-delivery device 111 has an inlet 12 into which lubricant (for example, grease) is introduced under high pressure. This pressure can be 50 bar or more.

The fluid-delivery device has a fixed ring body 13, as well as a shaft ring 14 rotating with the drive shaft, which is designed as a separate internal ring. An outlet 15 for the lubricant is arranged in the revolving shaft ring 14. A line 16 (only indicated schematically here) emerges from this outlet to a progressive distributor 17 (also shown only schematically), which ensures distribution of the lubricant. The lubricant goes from the progressive distributor 17 through lines 18, 19, and 20 to the friction sites, it being pointed out that the lines 18 to 20 are only examples of the total of nine lines. All lines 18 to 20, as well as the progressive distributor, rotate in unison with the rotating drive shaft.

FIG. 2 is referred to, in which an enlargement of the fluid delivery device 11 according to the invention is shown. The shaft ring 14 is designed in two parts in the embodiment example shown, the left part 21 having outlet 15 and engaging with a second part 22 of the shaft ring, which overlaps with its upper shoulder 23 a lower shoulder 24 of the left part 21. The shaft ring 14 is connected by a threaded connection 25 to a stop ring 26, which is welded in turn to the drive shaft. The weld is provided with reference number 27.

The fixed upper-ring body 13 is also designed in several parts. It has a main part 28, as well as two side parts 29, which are connected by a threaded connection 30 to the main part. Seals 31 (for example, radial shaft sealing rings) are provided between the fixed ring body 13 and the drive-shaft ring 14, which seal the shaft ring relative to the ring body. Rolling bodies 32 are also arranged between the shaft ring 14 and the ring body 13, on which the shaft ring 14, on the one hand, and the ring body 13, on the other, are supported. The rolling bodies 32 permit low-friction rotation of the shaft ring 14 and therefore the entire drive shaft 1, even with additional axial and/or radial loads.

The fluid-delivery device 11 according to invention functions as follows. Lubricant is admitted to the inlet 12 of the fixed ring body 13 at high pressure. The lubricant passes centrally through channel 33 through a rolling body 32 to outlet 15, from which it goes to the progressive distributor 17 through line 16. From there, it is distributed to the individual friction sites through lines 18 to 20 shown as examples. The rolling bodies 32 are arranged in the flow path of the fluid. This means that the rolling bodies 32 need not be lubricated separately. Instead, they are lubricated automatically, i.e., by passage of the lubricant. The lubricant likewise lubricates the seals 31 arranged on both sides of the rolling bodies. This guarantees a long lifetime. For replacement of seals 31, the threaded connections 30 are loosened and only the side parts 29 of the ring body 13 are removed. The seals 31 are therefore freely accessible.

The rotating ring body 14, as already mentioned, is also designed in two parts. The left part can be removed by loosening the threaded connection (not shown) between the left part 21 and the right part 22.

An opening 34 is provided in shaft ring 14, through which the line 19 can be guided to the correct joint depicted in FIG. 1 “behind” the fluid delivery device. The opening 34 can be designed as a hole, and it can be made at almost any location.

The rolling bodies 32 are designed as spheres. They run directly on bearing surfaces 35 to 38, which are formed by the shaft ring and the ring body, the bearing surfaces 35 and 36 being assigned to shaft ring 14 and the bearing surfaces 37 and 38 to ring body 13. Additional elements, which an ordinary roller bearing has, are not necessary. In particular, a cage can be omitted. The bearing surfaces 35 to 38 are arranged at an angle to the axial direction of the drive shaft 1. They can therefore advantageously take up both radial and axial forces.

LIST OF REFERENCE NUMBERS

-   1 Drive shaft -   2-9 Joint bearings -   10 Length compensation -   11 Fluid delivery device -   12 Inlet -   13 Ring body -   14 Shaft-ring section -   15 Outlet -   16 Line -   17 Progressive distributor -   18-20 Lines -   21 First part of the shaft ring -   22 Second part of the shaft ring -   23 Shoulder -   24 Shoulder -   25 Threaded connection -   26 Stop ring -   27 Weld -   28 Main part (of ring body) -   29 Side part (of ring body) -   30 Threaded connection -   31 Seals -   32 Rolling body -   33 Channel -   34 Opening -   35-38 Bearing surfaces 

1. A fluid-delivery device for a shaft comprising: a shaft-ring section assigned to the shaft, which rotates with the shaft during rotation of the shaft, a ring body arranged around the shaft ring section, fixed during rotation of shaft, which has an inlet for the fluid, rolling bodies arranged between the shaft-ring section and the ring body, on which the shaft-ring section and the ring body are supported, and a passage assigned to the shaft ring section, which is connected to the inlet.
 2. A fluid-delivery device according to claim 1, wherein the rolling bodies are arranged in a flow path of the fluid.
 3. A fluid delivery device according to claim 1, wherein the rolling bodies are enclosed in a fluid-tight manner by the shaft-ring section and by the ring body.
 4. A fluid-delivery device according to claim 1, wherein the shaft-ring section is designed in several parts.
 5. A fluid-delivery device according to claim 1, wherein the shaft-ring section forms bearing surfaces for the rolling bodies.
 6. A fluid-delivery device according to claim 1, wherein the ring body forms bearing surfaces for the rolling bodies.
 7. A fluid delivery device according to claim 5, wherein the bearing surfaces are arranged at an angle to a longitudinal axis of the shaft, to take up axial and radial forces.
 8. A fluid-delivery device according to claim 1, wherein the shaft ring section has an outlet for the fluid, arranged laterally (axially).
 9. A fluid-delivery device according to claim 1, wherein the shaft-ring section has at least one essentially axial passage for a fluid line.
 10. A fluid-delivery device according to claim 1, wherein the ring body is designed in several parts, preferably being capable of disassembly so that, when the fluid-delivery device is completely installed, at least one seal is accessible by removing a part.
 11. A fluid-delivery device according to claim 1, wherein a progressive distributor is provided, which is connected in terms of flow to the shaft ring section and rotates with the shaft.
 12. A fluid-delivery device according to claim 1, wherein the fluid delivery device is designed as a central lubrication device for lubrication of joints with lubricants, preferably grease. 